1. Field of the Invention
Example embodiments of the present invention relate to a nano-elastic memory device and a method of manufacturing the same. More particularly, example embodiments of the present invention are directed to a nano-elastic memory device that has an elastic body between two electrodes, wherein the length of the elastic body varies with an electrostatic force between the two electrodes to electrically connect and disconnect the two electrodes, and a method of manufacturing the same.
2. Description of the Related Art
The development and increasing popularity of electronic products has encouraged the development of memory devices for information storage. These memory devices need to be nonvolatile to retain information even if power is turned off. Also, to be competitive, the memory devices may require lower manufacturing costs, higher integration density, lower power consumption, and/or higher operation speed. A flash memory is an example of a nonvolatile memory device that has a drawback of relatively slow operation speed. Accordingly, various nonvolatile memory devices having a greater capacity than flash memory and the capability of operating at higher speeds have been developed.
Examples of these are magneto-resistance random access memory (MRAM) that uses magnetic spin direction, ferroelectric random access memory (FRAM) that uses the polarization of a ferroelectric material, and a phase change random access memory (PRAM) that uses a thin film phase change material whose phase is changeable by applying energy.
The versatility of carbon nanotubes (CNTs) has been proven in many fields since they were discovered in 1991. A memory device that uses CNTs has been developed as an example of a conventional nonvolatile memory device and is comparable to MRAM, the FRAM, and PRAM. A CNT memory device may make use of the bending characteristics of the CNT according to electrostatic force. CNT memory devices may be formed of CNT ribbons and electrode traces which form a cross-bar shaped array and the CNT ribbon may be formed in a bridge shape by a support unit located between the electrode traces.
The operation principle of the conventional CNT memory device is that if a voltage is applied to the CNT ribbon and another voltage of opposite polarity is applied to the electrode trace by driving a transistor, the CNT ribbon bends due to an electrostatic force and contacts the electrode trace formed between the support units so that the CNT memory device is in an ‘ON’ state. Alternatively, if voltages of the same polarity are applied to the CNT ribbon and the electrode trace, the CNT ribbon returns to the original position so the memory device is in an ‘OFF’ state. Accordingly, the convention CNT memory device may store data ‘1’ when the CNT ribbon contacts the electrode trace, and may store data ‘0’ when the CNT ribbon is not in contact with the electrode trace.
The bending of the CNT ribbon may be maintained by Van der Waals' force. The ‘ON’ state or the ‘OFF’ state may be read by measuring the resistance of an electrode that connects the electrode trace to the CNT ribbon after a current is supplied to the electrode trace. That is, information may be read by detecting whether the electrodes are connected and allow a current to flow. Once the CNT ribbon is bent, that state may be maintained even if power is turned off, making the convention CNT memory device a nonvolatile memory device.
However, when the conventional CNT memory device operates, memory cells may be affected by an adjacent memory cell due to mutual actions between neighboring memory cells, because more than one of the memory cells of the conventional CNT memory device may be connected by a single CNT. Also, because the conventional CNT has a ribbon or network shape, the driving voltage may be relatively large.